Halloween in Masked Mystery Mansion
by LadyShadow26
Summary: "Youre invited to a Halloween Party..." Shinichi Kudo receives a strange invitation marked from two figures he is all too familiar with. Night Baron and KID. Of course he has no choice but to attend. Can he solve the mystery before the night is through? (Post canon, Implied canon pairings)


_**Hello Everybody and welcome to the first chapter of Halloween in Masked Mystery Mansion! (Title may be subject to change...eventually)**_

 _ **Question: "But Shadow don't you have like half a dozen other stories you should be finishing? Answer: Yes. Yes I do. Unfortunately this particular monster wouldn't leave me alone and in the spirit of the Holiday I decided to get at least the first chapter up.**_

 _ **Plus Ive been suffering from quite a bit of writers block lately and unfortunately that+full time job equates to a lot of hours of stress. I hope you all at least enjoy what I have for you here. Hopefully a worthwhile "treat" for all those who love the Holiday as much as I do.**_

 _ **Okay so this piece has been mostly unbetaed. Any errors here are completely my own. Thanks to DisconsolateMist and BloodiedCoreOfHope for their partial assistance and continued support! Wouldnt be able to this without them.**_

 _ **Major disclaimer: I do not own these characters. All 30+ of em.**_

 _ **Warning: Some horror aspects present in this story. Nothing too extreme but be careful reading nonetheless.**_

 _ **All that said...ENJOY!**_

Shinichi Kudo stared up at the gothic style mansion looming above him, his eyebrow twitching in equal parts annoyance and awe. So this was the place, huh? They really had gone all out on this one… It looked like something straight out of an old Hollywood horror set. Unsurprising, given the ones who had chosen this place.

Even though he was still a bit annoyed at being forced out of the house for this, he had to admit his curiosity was slowly getting the better of him. After all, the invitation he had received had promised some very interesting… _characters_ to be present. In addition, several people who he knew had also received similar invitations. This, strangely enough, included a very insistent Ran, who was surprisingly willing to go, so long as _he_ was present.

Shaking himself out of his thoughts, he reached up and pulled with some effort on the traditional large black iron door knocker, coated heavily in dust and rust. It made a deep "thunk" each time it struck the wooden doors. Predictably, the door crept open with an ominous creak, supposedly ancient dust flying everywhere. Shinichi immediately took note of the cobwebs atop said door, as well as the disturbingly realistic spiders attached to them. Someone had clearly gone through an awful lot of trouble with the decorations.

Sighing deeply to himself in response to the over the top decorations, but also growing more curious by the moment, Shinichi stepped inside the mansion. The door quickly slamming behind him with a distinctive bang. To any lesser person such an effect would cause a start, but Shinichi, the detective who had stared death in the face on numerous occasions, it gave no cause for fear. After all this was only an elaborate set up reminding him of some sort of theme park ride. Though, if he were honest with himself, internally he was met with a small but deep well of emotions.

Shaking his head, he took a moment to assess his surroundings. The Foyer was rather dimly lit, setting the mood with several candelabra's with tall, dark coloured wax candles burning slowly and steadily. The walls were more modern looking than the exterior let on, but still held the illusion of something out of the early 19th century gothic revival. He smiled lightly to himself. Though he hated to admit it, there was something truly exciting about stepping into a piece of history.

He quickly took note that of the small table with a guest registry in the center of the room. It was illuminated by an elaborate glass chandelier overhead. Behind it stood a single figure whom he recognized almost instantly. "Professor!" The portly figure turned to face him. Shinichi quickly took note of the costume he was wearing. There were two large screws protruding from his pale painted head and stitch marks on his face.

"Ah, Shinichi-kun! I was wondering when you would arrive. The rest of the guests are already here. I was beginning to think you wouldn't come at all! Ran-kun has been rather impatient waiting for you to appear…" Under the makeup, Shinichi could see the Professor sweat-dropping.

Shinichi chuckled lightly to himself. He knew very well how Ran could be when she was nervous, and even worse when impatient. "Sorry, Professor. I got a little distracted... Here's my invitation! My guess would be that you're the footman here, am I right?" Shinichi gave his older friend a warm smile. No doubt the lovely hosts of this party had dragged Agasa in as part of their show.

Agasa returned with a chuckle of his own. "I suppose you could say that." He paused for a moment before continuing. "Please, first take a minute to sign the registry. Though, our hosts ask that you do not sign in with your real name, but a pseudonym."

Shinichi paused briefly, taking in that most curious fact, but quickly shrugged. As he picked up the black crow's feather quill and scanned the list of other guests before him he couldn't help but think back to what had drawn him here in the first place.

About a week before, he had received a letter in the mail containing an invitation to a rather strange sounding Halloween Party. This one, at least, was set to actually take place on October 31st. What had intrigued him wasn't the party itself, but the names of the ones who had sent out the invitation. He noticed them again proudly sitting in formal looking kanji handwriting at the very top of the guest list: Night Baron and Night Baroness.

Of course, he knew that this could all be a ploy by his parents to try and get him to socialize a bit more. Ever since defeating the Organization and returning to his regular body, Shinichi had become far more of a recluse than before. Heck, thinking back he was more social as Conan somedays.

Still, he knew if his parents were involved, there was most definitely something afoot here. Indeed, there was one other name here that caught his attention: XIV XII. 1412. The one who had disappeared from the public eye shortly after the Organization's downfall. KID.

Ever since that day Shinichi had found himself rather bored with regular cases. He still ran into murder cases almost daily, but much as he hated to admit it, the thief had been a good reprieve from the stress brought on by his constant run-ins with death.

He now, of course, knew the reason behind the thief's motives; having worked indirectly with him in the end, with an equal exchange of information that lead to the finding of both the antidote, and the jewel. He had even shortly thereafter developed a close relationship with the thief's daytime persona. Plain old Kaito Kuroba kept life interesting for him, though he had retired the cape officially.

Surprisingly, his pseudonym had appeared on the invitation beside Shinichi's parents. This worked well to arouse Shinichi's curiosity far enough to lure him into the obvious trap. He had known his father must have been aware of both of KIDs' personas, though his mother's knowledge was harder to deduce. After all, as Shinichi had later learned, she learned the art of disguise from the original's daytime persona.

The wording on the invitation had lead him to the conclusion that his parents and Kaito were working together on something, and of course, that meant trouble for himself in particular. He shook his head begrudgingly and finished signing the Pseudonym; "Sherlock Holmes". In all likelihood, he would find out soon enough what this was all about. He memorized the other guest names on the registry, though, he was unsure if it would come in handy later on or not.

Glancing back at Agasa, he put on a straight face acting the part of his pseudonym. Agasa nodded at him, smiling widely. "Well met, Mr. Holmes. I'll take your invitation and your coat for you, sir. Then you may join the other guests in the main ballroom."

Shinichi nodded handing him his dark coat. It worked out that he had chosen to dress as the fictional detective for the event rather than ignoring dress codes as he had occasionally done in the past for other such events. He had the typical detective hat handy with him as well as a casual suit underneath the coat he had been wearing, resembling _some_ of the movie iterations of the detective at least. Since KID was involved, he suspected there would be at least one more detective in Sherlock gear at the event, but the guest registry had revealed no such thing. Instead something rather unexpected.

Before leading him into the ballroom however, Agasa handed him another envelope with purple and gold trimming. "Here, take this. Your directions are as follows: do not open it until instructed to do so. Absolutely no exceptions. And please do remember that you are to keep in character as much as possible. I trust you understand?"

Shinichi paused, his curiosity steadily increasing with each new clue put in front of his nose to investigate. Calmly, he nodded and put a half smile on his face. "Thank you." He took the envelope and put it in his pants pocket as he strode behind the Professor into a larger room just beyond the entryway.

This room was much more well lit and Shinichi took note of the large group of costumed people scattered about the room. It really did look like he was the last to arrive. He quickly took notice of a small cluster of people standing at the outskirts of the room near the bookshelves. He would recognize the loudest voice of the crowd anywhere, even muffled as it was by the mask on his face.

"Hat-" he almost called out then remembered the rules. He didn't really care if he broke the rules, but it was most likely the hosts would never let him live it down, or worse, find some method of revenge. Thus he strode over with a smug gait, coming up beside them before calling out; "Hello! Crimson Dragon Thorn and Silver Knight, I presume?"

The two, who had obviously been arguing with each other, turned to face him. They blinked momentarily, seemingly checking over his costume, before recognition crossed their faces. The one dressed in rather elaborate red scales, complete with stylistic wings, a short uncumbersome tail, and a realistic horned lizard head mask spoke first. "Oi, Kudo! About time ya got here."

Shinichi sighed quietly to himself. So much for discretion... Apparently he wasn't the _only_ one to notice the slip up. The "Silver Knight" who Shinichi now was certain was Kazuha gave Heiji a shove. "Oi, idiot! Yer not supposed ta say his name!"

Beneath the mask, Shinichi noticed Heiji not-so-subtly roll his eyes. "It's not as if I don't know who he is 'zuha. He's not exactly wearin' da most discreet of costumes. Besides, I'm pretty sure he already had us both figured out da moment he heard yer yellin'."

"I'm not the one who was yellin', ahou! He probably heard ya from the next room over! Yer destroying all the hard work that was put into that costume, ya bumblin' dolt!" Kazuha continued to argue.

Meanwhile, a figure Shinichi recognized all too well next to them sighed and walked up to Shinichi, greeting him. "Hey, Sherlock. Glad you could make it." The woman clad in red and gold heroine armor clearly designed to fit to her curves smiled kindly at him, though there was something hidden there that he knew all too well. "I was beginning to think you weren't coming at all…"

Shinichi gulped slightly. He and Ran had developed a rather rocky relationship after the truth had come out about his exploits as Conan. Still, after some time had passed they had smoothed things over and started anew. Though, he did stay mostly out of karate chop range whenever possible. "Hello…Diana."

Ran gave him a playful glare before letting her smile soften. "Sherlock." She smiled lightly at him before holding out her braceleted hand for him to take. With a bit of hesitation, he took it. There was a quiet whistle from someone to the left, which caused Shinichi to quickly turn his head.

The one who had just whistled went silent, though there was still a grin apparent on her face. It took a moment for Shinichi to register who it was under the heavy looking wig and purposely overdone makeup. _"Queen of Hearts… interesting costume choice_ ," he thought to himself. He glanced behind the queen, noticing another formally dressed knight, this one obviously male. It wasn't hard to deduce these two identities given their faces were much less obscured than Heiji's. " _I'm surprised Makoto would agree to wear something like that… Still it is fitting all thing's considered_." He held out a hand in formal greeting to the red knight, the confident and dry smile of Holmes firmly in place.

Makoto returned his gesture shaking it in a firm grip further confirming his identity. "That costume really suits you." Shinichi commented lightly in a whispered tone.

Makoto nodded, though he seemed rather distracted. "Milady's first choice was KID, but I told her I'd prefer something else. Umm, excuse me, but aren't you that detective...The one everyone's always talking about?"

Shinichi nodded lightly, that question could actually refer to either himself, or his character really. This was actually his first time meeting Makoto in person as himself. Still, deciding to remain character he kept a straight face replying. "I believe so. Sherlock Holmes, at your service." He bowed.

"Ah, I see…" Makoto fell silent, though he returned the bowing gesture.

"You should watch yourself tonight detective, not everyone is who they seem." Someone had snuck up behind him, and he recognized the accent almost instantly. "Unmasking them is a true detective's job."

He turned around to face the new voice. "You'd probably know that better than most…Moriarty-san" he was greeted with the face of Saguru Hakuba dressed like his favorite fictional villain. Seemed he had guessed correctly.

He nodded "Indeed this entire party seems to have KIDs fingerprints all over it…" Hakuba stared off into the distance looking rather nostalgic, before turning back to face Shinichi. "I suppose you received the same invitation then?"

"Im pretty sure we all got da same invitation." Heiji broke in suddenly appearing to the left of Shinichi and placing a scaled hand on his friend's shoulder. "An' don't think just 'cause he's the one dressed as yer hero Sherlock he get's to have all da fun."

"Hmm. We shall see about that." Shinichi noticed a very devious looking grin on 'Moriarty's' face. Clearly he was getting into character. Shinichi had to admit the adrenaline was beginning to flood his veins as well. The three of them here, called by the same odd invitation. There was obviously more to this than he originally thought. He could understand Hakubas nostalgic look as he thought back on cases in the past that had come with similar invitations.

Suddenly the two other detectives turned looking past Shinichi their attention distracted. "Hey are you two…?" Before Shinichi could say anything more the lights dimmed in the room and a single spotlight shown on the center of the room.

"Shh it's startin'..." Heiji exclaimed in a muffled whisper as everyone else turned their attention to what was happening.

There stood Doctor Agasa in his Frankenstein monster garb clearing his throat lightly. "Attention everyone. It is time for the main event of the night to begin. As you are all well aware this party is sponsored by our illustrious hosts; the Great Night Baron and Baroness as well as their newest partner: KID."

There were several murmurs and a squeal coming from the Queen of Hearts direction. Shinichi stood stock still taking in the information with a crooked smile. This was it. This was what he was here for.

"Our hosts have created a challenge for you all. You were all handed an envelope tonight. In it contains information essential to this challenge. You may now open this envelope though do not show what's inside just yet." Agasa paused and there was shuffling of paper all around as envelopes were opened quickly by eager fingers.

Shinichi gazed at his own envelope before shrugging and opening it with a small rip. He pulled out the contents careful to keep them close to his person as instructed. The first thing he noticed was that there was a tarot card inside, and a little badge which presumably held a tracker or a speaker. Shinichi grinned to himself. Oh this was _definitely_ his parents doing.

He glanced at his other two detective friends. Heiji's face was difficult to read by the mask but his body language seemed to indicate that he was rather excited about something. Saguru, on the other hand still held that same smirk as earlier, though there was a bit of the signature detective contemplation in his eyes as well.

Suddenly there was a deep dark laugh that sounded throughout the room. A voice rang out as if through a loudspeaker. He recognized it almost instantly from his father's audiobooks and his own kidnapping case: Night Baron.

The laughter echoed throughout the hall. "Greetings dear guests and welcome to our main event. Tonight we have prepared a special surprise for you on this lovely Hallows eve."

A female voice broke in, Shinichi faintly registered it as that of his mother's, though it was somewhat different pitched than usual. "We issue to you a challenge. If you truly think you are worthy of the treasure we have taken than find it for yourselves! It is hidden here within this very mansion."

Suddenly KIDs voice broke in. "Now never let it be said 'There is no honor among thieves.' We gentlemen and lady thieves may be territorial, but we are hardly rude. Therefore… we have taken the liberty of leaving hints throughout the mansion as to the location of our prize."

There were excited murmurs among the crowd gathered though there were several hushed whispers as well. Shinichi glanced about gauging everyone's reactions. Most seemed rather excited by this information though some wore bored expressions as well. Hakuba had flinched initially, upon hearing KIDs voice, but was smiling much the same as earlier.

Night Barons voice interrupted with yet another low laugh. "However, don't expect us to just hand over what is our's. There is of course a catch to all this, and I think you'll find it rather _deadly."_

There were several loud slams and the sound of locks linking shut, as all the doors in room closed simultaneously

Suddenly there was a blood curdling scream that echoed throughout the room. Shinichi immediately turned his attention to it's source. There in the middle of the room stood a figure clothed in a black reaper's outfit. Next to the figure stood a wide eyed Jodie Starling,

dressed as a traditional witch, with a very realistic looking knife to her throat.

While others moved forward towards the cloaked figure in attempt to stop it, there was a bright flash and the lights went out in an instant. Moments later the light returned, but Jodie and the figure had both disappeared from where they were standing leaving no traces behind.

Night Barons voice rang out. "You have until midnight to find the treasure...be aware that every half hour one among you will be eliminated. If by the end of the time period no one has succeeded than you shall all remain here. Permanently." There was a deep cackle after this followed by several small screams.

Shinichi suddenly felt a presence attached in a death grip to his arm. He glanced over to see a shaking Ran who was still trying her best to wear a brave look on her face. Shinichi cursed under his breath. He knew his parents were rather dramatic, but to pull something like this… he shook his head. Now was not the time for such thoughts.

He put on a straight face, unsure how to give Ran reassurance in this case without completely breaking character. What would Holmes say in this case? His brain went through several iterations of the character before finally settling on the perfect quote for the situation. "Fear is wisdom in the face of danger, it is nothing to be ashamed of." He gave a sideways smile to Ran still holding a smug look on his face.

Ran flinched at the casual dismissal of her fear, before slowly letting her grip on his arm loosen as she knew what it meant. "I should have expected such a reaction from you…" She sighed, though Shinichi could still see some tenseness in her posture. She continued to hover next to him.

Shaking off the slight blush caused by her close proximity, Shinichi turned back to the center of the room where the incident had occurred. There was a small group gathered there, his two fellow young detectives among those searching the area just around it.

Slowly, Shinichi took in the faces of the other costumed guests in the area. He noticed a 'devil' figure standing over Heiji's shoulders glancing down at the scene below, a dumb look Shinichi would recognize anywhere on his face. Rans father. There was also an angel, who he recognized to be Ran's mother, and was that Kobayashi-sensei dressed as a mermaid? Both were speaking in hushed tones to each other.

On the outskirts of the group were Makoto and Sonoko. The Queen of Hearts had her face buried in her 'knights' shoulders. Meanwhile said knave held her protectively, glancing around with a deep blush that matched the shade of the outfit he was wearing. Kazuha the silver knight watched from afar with a look that seemed to be a mixture of anger and fear as she kept a close eye on her 'dragon'.

The rest of the guests were too far away for Shinichi to see in the limited light, but he could swear he saw a pair of glowing eyes in the distance looking at him directly. He felt a pulse go through him as their eyes connected briefly, but it faded as quickly as it came. Seemed he had found one of the hosts...

Speaking of… The loudspeaker voices had fallen silent for a moment, but Shinichi got the distinct feeling this was not the last he was going to hear of them.

In fact as if called by his thoughts the Night Baroness's voice suddenly spoke up though it was a good deal closer than before. Shinichi realized it was coming from the pumpkin pin he had removed from the envelope earlier. "You are all feel free to explore the mansion at your leisure now, but do keep in mind what has been said here."

Shortly after this was said the doors squeaked open leading the way into two separate hallways also dimly lit by candlelight. The room was filled with conversation as a couple of small groups split off in different directions.

Shinichi noticed that Heiji and Hakuba were among the two groups to leave the room each going a separate direction. There was a determined expression on Hakuba's face, and the way Heiji walked showed his determination more clearly than words could. The detectives were already on the hunt.

Shinichi glanced over at the center of the room. Kogoro lagged behind looking less than enthused. He seemed to be looking over the scene as if searching for any clues left behind from the event. Shinichi had to give him credit.

After 'Conan' had officially left the Mouri Detective Agency the 'Great Sleeping Kogoro' had at first fallen from the spotlight. Still, after discovering the truth behind his 'skill' he became a better person for it, striving to beat 'that detective brat' at his own game. He had genuinely started to apply himself as a detective again, though he still acted like a bumbling idiot at times.

Shinichi lingered at the side for a moment, putting a hand to his chin and thinking over all that had just occurred. He wasn't sure what to expect when he showed up here tonight, but a 'murder investigation' was not exactly his first thought. He had to wonder if KID himself was aware of that little twist. It seemed entirely out of character for him, and no doubt Hakuba was already on the case hounding the thief down, and confronting him about it. Heiji on the other hand was probably following the lead on the murder front, and had clearly seen something that had caught his eye.

Shinichi was so focused on his thoughts he didn't see Ran walk away to chat with Kazuha and Sonoko. Nor did he notice when the Professor casually snuck up behind him, and put a hand on his shoulder. Shinichi started a bit as he turned around to face the Professor. His time as Conan had made him a bit more wary when it came to people sneaking up behind him.

"Sorry to startle you. You seemed lost in thought. I was wondering if you needed any help... detective." Shinichi was shaken from his thoughts as he stared back at Agasa. "I am afraid I'm no stand in for Watson, but if there is any way I can assist you just let me know."

Shinichi smiled at his old friend though it was withdrawn as he remembered that he was still in character. He paused a moment weighing the options available to him in his mind. No doubt Agasa knew more about what was going on here. That fact was apparent the moment he greeted him at the door. Still he was obviously still playing his part, and it was likely he would have to choose his words wisely if he wanted to get any information at all.

"Actually… Could you tell me a bit more about this 'treasure?' I'd like to know what it is I am searching for so adamantly, that our hosts would go to such...lengths to protect it." Shinichi knew that he had chosen the correct phrasing as Agasa's face lit with recognition and he nodded in acknowledgement.

"Of course. Truth be told I only know a minimal amount about it myself, but rumors say that some time ago KID and Night Baron had an alliance. Though those same rumors say something happened that broke that alliance. It is said that what was stolen lies here within these mansions walls. A priceless treasure, only one is known to exist in this world."

Shinichi quickly took note of how vague, and almost scripted Agasa's answer sounded, though it was still more information than he had before. What stood out to him was that he had referred to KID and Night Baron's alliance in the past tense. So they weren't allied together now? He paused thinking this over. That added up with what he had been contemplating earlier. Murder wasn't KID's Baron on the other hand… His father had written the character to be rather morally ambiguous. Murder wasn't out of the question in that case.

There seemed to be a couple of separate plots going on here, and Shinichi knew exactly who to blame. He glanced around the room taking in the remaining faces. There were about ten or so people left behind including himself. This included three elaborately dressed guests that he hadn't quite taken note of before, when he first entered the room.

There was what looked like a Kappa, and a Fairy chatting next to a person who held their back to Shinichi, face completely obscured. Suddenly as if sensing Shinichi's gaze the person turned Shinichi could see now by the build that it was indeed a man, but there was something that made Shinichi's eyes widen. In his hand he held a rather realistic looking latex face. Though his own face was completely void of any features.

Shinichi found himself hiding a shudder suddenly as he stared at the mask which almost seemed to be smiling at him. The man turned away momentarily, and the next moment the mask was gone. It took another few moments for Shinichi to realize it was now sitting on the man's face. He held back from shivering as the man smiled at him with the same expression the mask held moments ago. Then just like that the man turned and walked away disappearing into the left hallway.

Shinichi watched him go, an ironically blank expression on his own face. His detective senses told him exactly what he needed to know. _Night Baron_. That was him. No doubt about it. However, Shinichi knew that unmasking him wouldn't be as simple as just going after him. He was too crafty for that, and more liable to lead him into a trap. Besides there were other things going on here.

If his father was truly involved in this scenario there were likely clues to be left behind. Subtle ones, but nonetheless something. Heiji had run out of the room rather quickly after the doors had been opened. Logically that meant there must have been some clue left behind.

Shinichi noticed out of the corner of his eye the two figures Night Baron had been speaking to split up and head to the two separate corridors. At this point Shinichi was unsure who to follow. Thus he returned to the center of the room where it seemed old man Kogoro had finally finished his examination. He was looking between the two halls as if unsure which way was the correct path to go.

Shinichi himself was rather lost. Glancing at the spot Heiji had been examining earlier, he didn't seem to find anything to indicate which direction he should go. Following the Night Baron still seemed like the obvious option, but he still didn't have any idea whether it was a trap or not.

The decision was made for him however, as a shrill feminine shriek rang out, echoing from the left hallway. Shinichi and Kogoro both ran quickly towards the source. However, they were too late. There lay Sumiko Kobayashi, knife in her chest, the same black figure from earlier, standing over her body. Just as before, the figure disappeared alongside the body, this time in a poof of smoke before anyone could grab them.

As the smoke cleared Shinichi took a quick glance at his watch. 7:31. He cursed under his breath. He had spent so much time trying to figure out which direction to go that he had completely forgotten the imposed 'time limit.' Now a second 'victim' had paid the price. Shinichi cursed again. This was going to be a lot more complicated than he first imagined and he had one person to thank for it.

Deep dark laughter echoed throughout the room, and Shinichi found himself clenching his fists. "Night Baron." he said aloud to no one in particular. With that, the rest of the room fell silent.

 _ **Thus ends chapter 1. Hope you all enjoyed. Any questions/comments and concerns please leave a review! I really do appreciate it! Until next chapter ;)**_

 _ **-LadyS**_


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